The nature of progenitors of the so-called super-Chandrasekhar candidate Type Ia supernovae ( SC-SNe Ia ) has been actively debated .
Recently , Yamanaka et al .
( 2016 ) reported a near-infrared ( NIR ) excess for SN 2012dn , and proposed that the excess originates from an echo by circumstellar ( CS ) dust .
In this paper , we examine a detailed distribution of the CS dust around SN 2012dn , and investigate implications of the CS dust echo scenario for general cases of SC-SNe Ia .
We find that a disk/bipolar CS medium configuration reproduces the NIR excess fairly well , where the radial density distribution is given by a stationary mass loss .
The inner radius of the CS dust is 0.04 pc .
The mass-loss rate of the progenitor system is estimated to be 1.2 \times 10 ^ { -5 } and 3.2 \times 10 ^ { -6 } M _ { \odot } yr ^ { -1 } for the disk and bipolar CS medium configurations , respectively , which adds another support for the single degenerate scenario .
Our models limit SN 2009dc , another SC-SN Ia , to have a dust mass less than 0.16 times that of SN 2012dn .
While this may merely indicate some variation on the CS environment among SC-SNe Ia , this could raise another interesting possibility .
There could be two classes among SC-SNe Ia ; the brighter SC-SNe Ia in a clean environment ( SN 2009dc ) and the fainter SC-SNe Ia in a dusty environment ( SN 2012dn ) .